Order 13. =Gnomoniaceæ.= Perithecia, with peak-like aperture. _Gnomonia
erythrostoma_ in the leaves of _Prunus avium_, which turn brown and do
not fall in autumn.
Orders 14–18. _Stroma generally well developed. The perithecia
are embedded in the stroma, but when this is rudimentary, in the
substratum._